Two-port valve

ABSTRACT

There is provided a two-port valve in which a deviation of a degree of parallelization of a valve member and a valve seat can be corrected automatically, which has excellent airtightness, and in which assembly and replacement of the valve member are easy. For this purpose, a shoulder portion  51  and a small-diameter portion  52  are formed in a vicinity of an end portion of a shaft  15 , a groove portion  55  into which a snap ring  54  is mounted is formed in a vicinity of a tip end portion of the small-diameter portion, a through hole into which the small-diameter portion  52  is inserted and an annular stepped portion formed by increasing a diameter of a portion of the through hole are provided to the valve member  25 , a sealant  65  for providing sealing between the shaft and the valve member is mounted to the stepped portion, a plate  66  is provided between the valve member  25  and the snap ring  54 , and the valve member  25  is locked while pressing the sealant  65  mounted to the stepped portion and while being pushed against the shoulder portion  51  by the snap ring  54  mounted into the groove portion  55  and the plate  66.

TECHNICAL FIELD

[0001] The present invention relates to a two-port valve for allowingand intercepting passage of fluid such as air, oil, water, and steam.

PRIOR ART

[0002] There is a known pilot-type two-port valve in which a pilot valveis switched to supply or discharge pressure fluid to and from a pressureoperating chamber on one face side of a pressure-receiving body such asa piston and a diaphragm to move up and down the pressure-receiving bodyand a valve member connected to the pressure-receiving body through avalve stem to open and close a valve seat, thereby connecting andseparating an input port and an output port for the pressure fluid toand from each other by opening and closing of the valve seat.

[0003] A known pilot-type two-port valve 100 shown in FIG. 4 as anexample includes a main valve 101 having an input chamber 103 into whichpressure fluid is introduced from an input port, an output port 104, avalve seat 105 in a flow path connecting the ports, and a valve member106 for opening and closing the valve seat 105 and a pilot valve 102. Inthe main valve 101, the valve seat 105 is opened and closed by movingthe valve member 106 up and down through a valve stem 107. Apressure-receiving body (a diaphragm in this example) 108 is secured tothe valve stem 107 and the valve stem 107 is constantly pushed in avalve-closing direction by a return spring 109. The pressure-receivingbody 108 is moved up and down by supplying and discharging the pressurefluid to and from the pressure operating chamber 110 by the pilot valve102.

[0004] In the above known pilot-type two-port valve 100, a first steppedportion 114 and a second stepped portion 115 formed of shoulder portionsand small-diameter portions extending in an axial direction are formedat a lower portion of the valve stem 107, an external thread is formedat an outer periphery of the small-diameter portion of the secondstepped portion 115, the valve member 106 and a receiving plate 116 arerespectively fitted over the small-diameter portions of the firststepped portion 114 and the second stepped portion 115, the valve member106 is pushed against the shoulder portion of the first stepped portion114 through the receiving plate 116 to mount the valve member 106 to thevalve stem 107 by screwing a nut 117 over the small-diameter portion ofthe second stepped portion 115.

[0005] However, in this type of pilot-type two-port valve 100, becausethe valve member 106 is pushed against the valve stem 107 through thereceiving plate 116 by screwing the nut 117 in mounting the valve member106 to the valve stem 107, there are the following problems (1) to (4).

[0006] A two-port valve that is not the pilot type essentially has thesimilar problems.

[0007] (1) Because the valve member is fixed to the valve stem throughthe nut, it is difficult to obtain a satisfactory degree ofparallelization of the valve member and the valve seat and airtightnessis poor.

[0008] (2) Because it is necessary to screw the nut while fixing thevalve stem, assembly is not easy and replacement of the valve member isnot easy either.

[0009] (3) Because it is necessary to take measures against loosening ofthe nut and an assembly property and reliability are poor.

[0010] (4) It is necessary to subject the valve stem to thread cuttingand rotation preventing processing and cost increases.

DISCLOSURE OF THE INVENTION

[0011] It is an object of the present invention to provide a two-portvalve in which a deviation of a degree of parallelization of a valvemember and a valve seat can be corrected automatically, which hasexcellent airtightness, in which assembly and replacement of the valvemember are easy, which has excellent assembly property and reliability,and in which cost can be reduced.

[0012] To achieve the above object, a two-port valve of the inventioncomprises a valve body including an input port and an output port forpressure fluid, a valve seat in a flow path connecting the ports, and avalve member for opening and closing the valve seat, wherein a shaft fordriving the valve member for opening and closing has at its tip endportion a shoulder portion, a small-diameter portion extending in anaxial direction from the shoulder portion, and a groove portion which isformed in a vicinity of a tip end portion of the small-diameter portionand into which a snap ring is mounted, the valve member has a throughhole into which the small-diameter portion of the shaft is inserted andan annular stepped portion formed by increasing a diameter of a portionof the through hole, and the stepped portion being mounted with asealant for providing sealing between the shaft and the valve member,and the valve member is locked while being pushed against the shoulderportion by the snap ring mounted into the groove portion through theplate.

[0013] In the two-port valve of the invention, it is preferable that thestepped portion formed in the through hole of the valve member is formedby increasing the diameter of the through hole on a tip end side of theshaft and that the valve member is pushed against the shoulder portionthrough the sealant mounted to the stepped portion by the plate or thatthe shoulder portion of the shaft is tapered and a portion of the valvemember pushed against the shoulder portion has a taper that issubstantially similar to a taper of the shoulder portion.

[0014] The two-port valve may be a pilot-type two-port valve for drivinga valve member with pilot fluid pressure, the valve member is connectedto a piston driven for opening and closing of the valve seat through ashaft, and a pressure operating chamber to and from which the pilotfluid pressure is supplied and discharged is formed on one side face ofthe piston.

[0015] In mounting of the valve member and the shaft to each other inthe two-port valve, the valve member is fitted over the small-diameterportion formed on the shaft, the sealant is mounted to the steppedportion of the valve member, and the plate fitted over thesmall-diameter portion pushes the valve member through the sealant toresiliently push the valve member against the shoulder portion of theshaft. In this state, a diameter of the snap ring is increased, the snapring is fitted over the small-diameter portion, and the diameter of thesnap ring is reduced in a position of the groove portion formed at thesmall-diameter portion to mount the snap ring into the groove portion.

[0016] Therefore, the valve member is locked by the snap ring mountedinto the groove portion of the shaft in a state in which the platepresses the sealant against resilience of the sealant and pushes thevalve member against the shoulder portion of the shaft.

[0017] By carrying out the operations in a reverse order, the valvemember can be detached from the shaft.

[0018] As described above, because the valve member is not fixed to theshaft but is locked resiliently by the snap ring through the plate inthe two-port valve of the invention, the valve member can be seatedalong the valve seat, a deviation of a degree of parallelization of thevalve member can be corrected automatically, and the shaft isunnecessary to be subjected to thread cutting and rotation preventingprocessing of a nut.

[0019] The plate is locked by the snap ring, which provides measuresagainst loosening. Because sealing is provided between the shaft and thevalve member by the sealant mounted to the stepped portion of the valvemember, sealing is reliable.

BRIEF DESCRIPTION OF THE DRAWINGS

[0020]FIG. 1 is a vertical sectional view of an essential portion of anembodiment of the present invention.

[0021]FIG. 2 is an exploded view of a valve member of the presentinvention.

[0022]FIG. 3 is an enlarged sectional view of the valve member of theinvention after assembly.

[0023]FIG. 4 is a vertical sectional view of an essential portion of aknown pilot-type two-port valve.

DETAILED DESCRIPTION

[0024]FIG. 1 is a vertical sectional view of an essential portion of anembodiment in which the present invention is applied to a pilot-typetwo-port valve. A valve member on a left side of a center line is in anopen state while a valve member on a right side of the center line is ina closed state.

[0025] The pilot-type two-port valve 1 includes a main valve (two-portvalve) 2 and a pilot valve 3 mounted to the main valve 2. The main valve2 has a valve body 4, a cover 5 airtightly mounted to the valve body 4,a piston 18 for sliding in the cover 5, and a valve member 25 mounted toa shaft 15 of the piston 18. The valve body 4 has an input port 6 and anoutput port 7 for pressure fluid, a valve seat 8 provided in a flow pathconnecting the ports, a mounting portion 9 to which the valve seat 8 ismounted, and an opening 10 provided to open into the cover 5 in aposition facing the mounting portion 9, and the valve member 25 foropening and closing the valve seat 8 is mounted in a flow path of thevalve body. The cover 5 has a space portion 17 for housing the piston 18and the shaft 15 and a pilot port 11 and a breathing port 12 areprovided to a vicinity of an upper portion of the cover 5.

[0026] A lower portion of the space portion 17 formed in the cover 5opens into the opening 10 of the valve body 4 and a spacer 16 having athrough hole through which the shaft 15 passes is housed airtightly in amouth portion 14 on the open side.

[0027] The piston 18 secured airtightly to the shaft 15 is housed in thespace portion 17 above the spacer 16. An outer peripheral wall of thespace portion 17 functions as a cylindrical face on which the piston 18slides airtightly. A spring chamber 17 a is formed above the piston 18and a pressure operating chamber 17 b is formed between the piston 18and an upper face of the spacer 16.

[0028] A circular ceiling portion 60 having a depression 19 at a centerof the ceiling portion 60 is formed above the space portion 17. Theceiling portion 60 limits an upward movement position of the piston 18and a partition 22 in a shape of a hollow cylinder is formed to projectfrom an upper portion of the depression 19. A space portion 21 in thepartition 22 is a space portion into which an extending portion 15 b ofthe shaft 15 is fitted and inserted and a bearing 24 for guiding theshaft 15 and a sealant 23 for sealing a periphery of the shaft 15 areprovided to the partition 22 at an outer periphery of the space portion21.

[0029] An annular space portion 19 a is formed between the partition 22and an outer peripheral wall of the depression 19 and a return spring 20for acting on and constantly biasing the piston 18 downward is housed inthe depression 19 including the annular space portion 19 a.

[0030] The spacer 16 is in a cylindrical shape having small-diameterportions 16 a and 16 b in vicinities of upper and lower end portions ofthe cylinder, a large-diameter portion 16 c between the small-diameterportions 16 a and 16 b, and a through hole in a central portion of thecylinder. The lower small-diameter portion 16 b is inserted into theopening 10 of the valve body. A lower end face of the large-diameterportion 16 c is supported by a body wall at a periphery of the opening10 and sealed by a sealant 31 mounted in an annular groove on the bodywall provided to surround the opening 10. An upper end face of thelarge-diameter portion 16 c is positioned by a snap ring 26 mounted inan annular groove portion in an upper portion of the mouth portion 14.An annular groove in which a sealant 27 is to be mounted is formed in anouter peripheral face of an upper portion of the large-diameter portion16 c. On the other hand, a bearing 50 for guiding the shaft 15 ismounted in a vicinity of an upper end of a peripheral wall of thethrough hole of the spacer 16 through which the shaft 15 passes. Annulargrooves in which sealants 28, 29, and 30 are to be mounted arerespectively formed between a lower end of the peripheral wall of thethrough hole and the bearing 50 and the annular sealants 28, 29, and 30are respectively mounted in the respective annular grooves.

[0031] The sealant 27 is a sealant for separating the pressure operatingchamber 17 b and outside air from each other. The sealant 28 is asealant (scraper) for scraping off filth and the like deposited on theshaft. The sealant 29 is a sealant for preventing entry of fluid fromthe valve body side. The sealant 30 is a sealant for sealing pressure inthe pressure operating chamber 17 b.

[0032] The shaft 15 has a smaller diameter on an upper side of a portionwhere the piston 18 is mounted than at a portion where the shaft 15passes through the spacer 16. An upper portion of the shaft 15 is housedin the space portion 21 and a lower portion of the shaft 15 passingthrough the spacer 16 and extending into the valve body 4 has a reduceddiameter and is airtightly mounted with the valve member 25 for openingand closing the valve seat 8 through a sealant 34.

[0033] Piston packing 33 is mounted to a periphery of the piston 18, thespring chamber 17 a above the piston 18 communicates with the breathingport 12, and the pressure operating chamber 17 b communicates with thespace portion 21 through a through hole 15 a formed in the shaft 15. Ifthe pilot valve 3 is mounted onto the cover 5, the space portion 21communicates with the pilot port 11 or the breathing port 12 through thepilot valve 3 as shown in FIG. 1.

[0034] If the space portion 21 is separated from the breathing port 12and communicates with the pilot port 11 simultaneously by switching ofthe pilot valve 3, pressure fluid from the pilot port 11 is supplied tothe pressure operating chamber 17 b through the through hole 15 a.Therefore, the piston 18 is pushed up by the pressure fluid againstspring force of the return spring 20. As a result, the valve member 25moves upward through the shaft 15 to which the piston 18 is secured.Thus, the valve seat 8 opens and the pressure fluid in the input port 6flows into the output port 7.

[0035] On the other hand, if the space portion 21 is separated from thepilot port 11 and communicates with the breathing port 12 by switchingof the pilot valve 3, the pressure fluid in the pressure operatingchamber 17 b flows out from the breathing port 12 through the throughhole 15 a and the space portion 21. Therefore, the piston 18 is pusheddown by the spring force of the return spring 20. As a result, the valvemember 25 moves downward through the shaft 15 to which the piston 18 issecured. Thus, the valve seat 8 closes and the pressure fluid in theinput port does not flow into the output port.

[0036] Although the space portion 21 is connected to the pilot port 11or the breathing port 12 by providing the pilot valve 3 onto the cover 5in the embodiment, the pilot-type two-port valve is not necessarilylimited to this.

[0037] For example, it is also possible to introduce pilot fluidpressure into the pilot port 11 from outside through a three-port valve(not shown). In this case, the pilot port 11 merely has to be connectedto the space portion 21 and the pilot valve 3 shown in FIG. 1 may beomitted. Because the pressure fluid in the space portion 21 is suppliedand discharged by switching the tree-port valve in this case, it isunnecessary to connect the space portion 21 to the breathing port 12.

[0038]FIGS. 2 and 3 show details of a connecting structure of the shaft15 and the valve member 25. FIG. 2 is an exploded view of the valvemember and FIG. 3 is an enlarged sectional view of the valve memberafter assembly.

[0039] The shaft 15 has in a vicinity of a tip end portion thereof atapered (saucer-shaped) shoulder portion 51 with a diameter graduallyreducing toward the tip end and with a large taper angle and asmall-diameter portion 52 extending from a position of the shoulderportion toward the axial tip end. A taper 53 is formed at a tip endportion of the small-diameter portion 52 and a groove portion 55 whichis adjacent to the taper 53 and into which a snap ring 54 is mounted isformed above the taper 53.

[0040] The valve member 25 is in a disc shape and has a through hole 61into which the small-diameter portion 52 of the shaft 15 is inserted ata center portion of the valve member 25. A diameter of one end portionof the through hole 61 on the tip end side of the shaft 15 is partiallyincreased to form an annular stepped portion 62 and the other end of thethrough hole 61 is formed with a tapered portion 63 whose diameter isincreased to have a taper substantially similar to that of the shoulderportion 51.

[0041] A sealant 65 for providing sealing between the small-diameterportion 52 of the shaft 15 and the valve member 25 is mounted to thestepped portion 62. The valve member 25 is locked through a plate 66having a through hole into which the small-diameter portion 52 of theshaft 15 is inserted while being pushed against the shoulder portion 51by the snap ring 54 mounted into the groove portion 55. An annularsealant 65 formed of a resilient member has a size in an axial directionof the shaft larger than a depth of the stepped portion 62 when thesealant 65 is mounted to the stepped portion 62 as shown in FIG. 3.Therefore, when the plate 66 is mounted by the snap ring 54 mounted intothe groove portion 55, the valve member 25 is resiliently pushed againstthe shoulder portion 51 through the sealant 65 by the plate 66. The snapring 54 is formed by curving a resilient metal wire into a C shape.

[0042] Assembly of the valve member 25 is carried out as follows.

[0043] In mounting the valve member 25 to the shaft 15, the valve member25 is fitted over the small-diameter portion 52 formed in a vicinity ofan end portion of the shaft 15 and the sealant 65 is mounted to theannular stepped portion 62. Then, the plate 66 is fitted over thesmall-diameter portion 52 and the tapered portion 63 of the valve member25 is pushed against the tapered shoulder portion 51 of the shaft 15 bypushing the sealant 65 and the valve member 25 by the plate 66. In thisstate, a diameter of the snap ring 54 is increased and the snap ring 54is fitted over the shaft 15. By reducing the diameter of the snap ring54 in a position of the groove portion 55 provided to the small-diameterportion 52, the snap ring 54 is mounted into the groove portion 55.

[0044] Therefore, the valve member 25 is locked to the shaft 15 throughthe plate 66 by the snap ring 54 mounted into the groove portion 55 ofthe shaft 15 in a state in which the plate 66 pushes the tapered portion63 of the valve member 25 against the tapered shoulder portion 51 of theshaft 15 while pushing the sealant 65 against resiliency of the sealant65.

[0045] Thus, the valve member 25 is mounted to the shaft 15. By carryingout the operations in a reverse order, the valve member 25 can bedetached from the shaft 15.

[0046] Because the valve member 25 is not fixed to the shaft 15 througha nut or the like but is locked by the snap ring 54 through the plate 66in this pilot-type two-port valve, the valve member 25 can be seatedalong the valve seat 8, a deviation of a degree of parallelization ofthe valve member 25 can be corrected automatically, and the shaft isunnecessary to be subjected to thread cutting and a rotation preventingprocessing of a nut.

[0047] The plate 66 is locked by the snap ring 54, which providesmeasures against loosening. Therefore, the shaft is unnecessary to besubjected to the thread cutting and the rotation preventing processingof the nut, assembly and replacement of the valve member are easy, anassembly property and reliability are enhanced, and cost reduces.

[0048] Because sealing is provided between the shaft 15 and the valvemember 25 by the sealant 65 mounted to the stepped portion 62 of thevalve member 25, sealing is reliable.

[0049] As described above, according to the invention, it is possible toprovide a two-port valve in which the deviation of the degree ofparallelization of the valve member and the valve seat can be correctedautomatically, which has an excellent sealing property, in whichassembly and replacement of the valve member are easy, which hasexcellent assembly property and reliability, and the cost of which canbe reduced.

What is claimed is:
 1. A two-port valve comprising a valve bodyincluding an input port and an output port for pressure fluid, a valveseat in a flow path connecting said ports, a valve member for openingand closing said valve seat, and a shaft for causing said valve memberto carry out opening and closing operations, wherein said shaft has at atip end portion thereof a shoulder portion, a small-diameter portionextending forward in an axial direction from a position of said shoulderportion, and a groove portion which is formed in a vicinity of a tip endportion of said small-diameter portion and into which a snap ring ismounted, said valve member has a through hole into which saidsmall-diameter portion of said shaft is inserted and an annular steppedportion formed by increasing a diameter of a portion of said throughhole, said stepped portion housing a sealant for providing sealingbetween said valve member and said shaft, and said valve member and anannular plate are successively fitted over said small-diameter portionof said shaft and said plate is fixed to said shaft by said snap ringmounted into said groove portion so as to mount said valve member tosaid shaft in a state in which said valve member is pushed against saidshoulder portion.
 2. A two-port valve according to claim 1 , whereinsaid stepped portion formed in said through hole of said valve member isformed by increasing said diameter of an end portion of said throughhole on a tip end side of said shaft and said valve member is pushedagainst said shoulder portion through said sealant by bringing saidplate into pressure contact with said sealant housed in said steppedportion.
 3. A two-port valve according to claim 1 , wherein saidshoulder portion of said shaft has a tapered shape and a portion of saidvalve member pushed against said shoulder portion has a taper that issubstantially similar to a taper of said shoulder portion.
 4. A two-portvalve according to claim 2 , wherein said shoulder portion of said shafthas a tapered shape and a portion of said valve member pushed againstsaid shoulder portion has a taper that is substantially similar to ataper of said shoulder portion.
 5. A two-port valve according to claim 1, wherein said two-port valve is a pilot-type two-port valve for drivinga valve member with pilot fluid pressure, said valve member is connectedto a piston driven for opening and closing of said valve seat through ashaft, and a pressure operating chamber to and from which said pilotfluid pressure is supplied and discharged is formed on one side face ofsaid piston.